Polyphenylene ethers (PPE) as well as blends prepared therefrom constitute an invaluable class of engineering thermoplastic resins. Resins of polyphenylene ethers are characterized by a unique combination of chemical, physical and electrical properties. For instance, they have favorable heat deflection temperatures and generally display high impact strengths. As a result of this unique combination of properties, resins of polyphenylene ethers are suitable for a broad range of commercial applications.
Typically, polyphenylene ethers are prepared via the oxidative coupling of phenols at low temperatures (about 35.degree. C.) in the presence of a catalyst, and the oxidative coupling is carried out in an organic solvent such as toluene. Subsequent to polymerizing, solid polymer is isolated by precipitation with non-solvents like methanol. However, the typical oxidative coupling method is not always desirable, since among other reasons, it results in linear polymer which does not have favorable flow capabilities and because it requires environmentally unfriendly solvents.
It is of increasing interest to prepare polyarylene ethers like polyphenylene ethers by a method which does not, for instance, require the use of hazardous solvents and which results in branched polymers having better flow properties than linear polymers at about the same intrinsic viscosity.
The instant invention, therefore, is directed to a novel method for making branched polyarylene ethers without requiring the use of such solvents.